Batteries comprising a positive electrode and a negative electrode separated by an electrolyte comprising a lithium salt in solution in a solvent are widely known. The operation of these batteries is provided by the reversible circulation of lithium ions in the electrolyte between the electrodes. The positive electrode is generally composed of a composite material comprising an active material, a binder, a material conferring electron conduction and optionally a compound conferring ionic conduction. The compound conferring electron conduction can be a carbon black which does not catalyze the oxidation of the electrolyte at a high potential.
It is known to use a γ-LixV2O5 compound as positive electrode active material in a battery operating by exchange of lithium ions between the anode and the cathode through the electrode. A process for the preparation of γ-LiV2O5 is described by J. Barker et al. [Journal of the Electrochemical Society, 150, (6) A684-A688 (2003)]. Said process consists in preparing a mixture of Li2CO3, of V2O5 and of carbon, in compressing the mixture, in order to form pellets therefrom, and in then subjecting the pellets to a heat treatment under an argon atmosphere in a furnace at 600° C. for 60 min. It is specified that, at a temperature of 525° C., a time of 10 hours is required to obtain pure γ-LiV2O5. In addition, U.S. Pat. No. 6,716,372 describes a process which consists in mixing Li2CO3, V2O5 and carbon, in compressing the mixture, in order to form pellets therefrom, in bringing the mixture to a temperature between 400° C. and 650° C. at the rate of 2° C./min, in maintaining at this temperature for a certain time and in then allowing to cool at the rate of 2° C./min. The duration of the maintenance at high temperature is of the order of 1 hour for 600 or 650° C. and of the order of 8 hours for 500° C.
The aim of the present invention is to provide a simple and inexpensive process for the preparation of a material composed of pure γ-LiV2O5 or of γ-LiV2O5 as an intimate mixture with carbon.